A study on the modeling of parameters affecting the IR drop mechanism in the initiation stage of crevice corrosion

The sizable potential difference between the crevice: mouth and the crevice tip is difficult to explain from theories mainly based on the chemical changes in crevice solution. In this study, the IR drop theory was adopted to explain the initiation of crevice corrosion in the framework of IR drop in the crevice electrolyte. Furthermore, the parameters linking the two components of potential drop - one due to accumulated charges from chemical changes of ionic species by mass transfer and the physical one caused by the current path through the crevice electrolyte - are examined. The mathematical model is constructed and the IR drop in the crevice is calculated using the FVM method. The chemical composition change in the crevice solution can affect the IR drop behavior through the intermediate parameter form of ion conductivity and viscosity, etc., together with the potential difference generated by the electric charge of locally charged ions. Viewed in this light, it can be concluded that the initiation mechanism only by IR drop is insufficient to explain the initiation of crevice corrosion in stainless steels that have very strong passivity.